There is something seriously wrong with my Twinkle

[Reeses]

It started out as a black spot. I didn't think anything of it--I got a new grow-light not long ago, and i thought it had gotte a small burn. Now the spots are spreading. There are also brown spots on the pseudobulbs, and there are strange, streaky-looking patches on the leaves. None of my other 'chids is affected.

I think it might be some sort of bacterial or fungal infection, but i've never dealt with one of those before. How do I treat this?

It was also repotted recently, but l used fresh mix from repotme and I always sterilize my tools with a flame.

[Reeses]

A better view of the leaves

[Leafmite]

That doesn't look good at all.
Have you tried a fungicide that contains copper?

[Reeses]

Leafmite, i have not! All i have is Physan. Do you think that would work? Is there a certain one you would recommend?

[Leafmite]

I don't use anything on the orchids so I wouldn't know what would be best. Someone at my OS recommended a product for someone else but I don't remember the name.

Here is an interesting link that might be helpful:

http://www.smokymtnorchidsociety.com...idDiseases.pdf

---------- Post added at 11:45 PM ---------- Previous post was at 11:43 PM ----------

Here is that famous link to help you determine what exactly is happening with your orchid:

http://staugorchidsociety.org/PDF/Or...ySueBottom.pdf

[Reeses]

Thanks for that!! I think it seems most like a fungal infection, maybe two at once. I will start dosing with Physan immediately and look into some containing copper.

You must have great care and conditions!

[estación seca]

The pseudobulb looks as though it had a wound, through which the fungus entered. Fungi normally enter plants either through the stoma on the leaves or through wounds elsewhere.

Fungicides applied now will not kill fungus growing in the tissues. You need to do some surgery. Unpot the plant and cut off pseudobulbs with rot. Cut off the leaves below the lowest spots. Sterilize your tool between cuts with 10% household bleach solution or 70% alcohol and let it dry before using it.

Systemic fungicides are taken up into the plant and prevent fungus from getting a foothold. They need to be in the plant before the fungus enters. Non-systemic fungicides may treat infestations on the leaves, because the leaves are so thin, but they will not help with infected pseudobulbs. Physan is a general disinfectant that works only on the surfaces it hits. I would not expect it to help you at all.

Very healthy plants are much less susceptible to fungus infection. This generally means good light, proper humidity and temperature, and adequate feeding, including calcium.

[orchid_infant]

I lost a whole oncidium plant last year to this kind of rot. I tried everything. Leaf spots aren't a huge problem. But as soon it hits the the PBs, its a different story.

Best approach would be to amputate the affected pseudobulb with some part of healthy tissue and sterilize the cuts with 5% H2O2 or alcohol. After that spray the whole plant heavily with a systemic + contact fungicide. There is a brand of fungicide which has carbendazim + mancozeb combination. Don't give too much moisture to the plant or the rot will spread quickly. Again as its an oncidium, it wil suffer if you keep it too dry. Its going to be a tricky situation. Best of luck!

[bil]

Originally Posted by orchid_infant

I lost a whole oncidium plant last year to this kind of rot. I tried everything. Leaf spots aren't a huge problem. But as soon it hits the the PBs, its a different story.

Best approach would be to amputate the affected pseudobulb with some part of healthy tissue and sterilize the cuts with 5% H2O2 or alcohol. After that spray the whole plant heavily with a systemic + contact fungicide. There is a brand of fungicide which has carbendazim + mancozeb combination. Don't give too much moisture to the plant or the rot will spread quickly. Again as its an oncidium, it wil suffer if you keep it too dry. Its going to be a tricky situation. Best of luck!

The only change I would make to the above advice would be, Mancozeb comes as a powder. When you have removed the dodgy tissue, dust the cut surfaces with the powder. I would leave that to dry, and maybe spray the whole plant with a Mancozeb solution.
Or maybe better, spray the plant, let that dry and then dust the cut.

[Leafmite]

Originally Posted by Reeses

You must have great care and conditions!

No, I have lost orchids to infections when I am not diligent enough with the calcium or when it is a new plant that hasn't been in my care long enough. Many years ago, I lost most of my collection to 'Black Rot' initiated by Calcium deficiency. I have used fungicides (Captan) on our fruit trees and a product (don't remember the name) that fought Fire blight on a pear (it is caused by bacteria) but I have never tried any of this stuff on my orchids.